Follow-Up and lead survival Data
Of the 77 patients who underwent epicardial pacemaker implantation, 4 patients expired in the first 30 days after implant (three with unipolar non-steroid-eluting leads, and one with bipolar steroid-eluting). Three other patients also passed away 8, 12, and 19 months after pacemaker implantation (all unipolar non-steroid-eluting leads). Their death was not related to lead malfunction. One patient was lost to follow up due to not presenting for reevaluation. None of them underwent lead replacement and just had one lead. Therefore, 81 remaining leads were followed. The epicardial lead failure occurred in 22 of 81 followed implantations (27.16%). The reason for failure included high threshold or loss of capture (16 implants), decreased EF due to RV pacing (one implant), lead fracture (one implant), and infection (four implants) (Table 5). Infected implants were not included in the survival analysis because of their failure reason that was not related to the lead characteristics. Therefore, 77 leads were enrolled in the survival analysis; 50 unipolar non-steroid-eluting and 27 bipolar steroid-eluting leads (see Supplementary Table 4 and 5).
The leads that were included in the survival analysis were followed for an average length of 25.81 months (SD, 11.70); ranged from 0.5 month (the lowest time to lead malfunction) to 48 months (one implant). The rate of lead failure was 23.37% (18 of 77 leads); 17 unipolar non-steroid-eluting and one bipolar steroid-eluting lead. The average time to lead failure was 18.20 months (from 0.5 to 44 months); 18.34 months for unipolar non-steroid-eluting (from 0.5 to 44), and 16 months for bipolar steroid-eluting leads. Bipolar steroid-eluting implants showed a significantly lower risk of failure; crude Weibull HR: 0.13 (95%CI, 0.02-0.99), and age-adjusted Weibull HR: 0.13 (95%CI, 0.02-0.96, p-value=0.045 (Figure 1).
Age, gender, and ventricular location (Figure 2) did not statistically significant affected the risk of failure. Pacing threshold over 3 µJ at hospital discharge was not correlated with higher hazards of lead failure (HR: 2.12 (95%CI, 0.48-9.28) p-value=0.32) (Table 6)